LARA TECHNOLOGIES EXAM_SPECIALSIX SECTION-1

Transcription

1 Q: 01. SECTION-1 Q: 02 Given: 12. import java.io.*; 13. public class Forest implements Serializable { 14. private Tree tree = new Tree(); 15. public static void main(string [] args) { 16. Forest f = new Forest(); 17. try { 18. FileOutputStream fs = new FileOutputStream("Forest.ser"); 19. ObjectOutputStream os = new ObjectOutputStream(fs); 20. os.writeobject(f); os.close(); 21. catch (Exception ex) { ex.printstacktrace();

2 24. class Tree { What is the result? A. Compilation fails. B. An exception is thrown at runtime. C. An instance of Forest is serialized. D. An instance of Forest and an instance of Tree are both serialized. Q: 03 Q: 04 Assuming that the serializebanana() and the deserializebanana() methods will correctly use Java serialization and given: 13. import java.io.*; 14. class Food implements Serializable {int good = 3; 2

3 15. class Fruit extends Food {int juice = 5; 16. public class Banana extends Fruit { 17. int yellow = 4; 18. public static void main(string [] args) { 19. Banana b = new Banana(); Banana b2 = new Banana(); 20. b.serializebanana(b); // assume correct serialization 21. b2 = b.deserializebanana(); // assume correct 22. System.out.println("restore "+b2.yellow+ b2.juice+b2.good); // more Banana methods go here 50. What is the result? A. restore 400 B. restore 403 C. restore 453 D. Compilation fails. E. An exception is thrown at runtime. Q: 05 Which three statements concerning the use of the java.io.serializable interface are true? (Choose three.) A. Objects from classes that use aggregation cannot be serialized. B. An object serialized on one JVM can be successfully deserialized on a different JVM. C. The values in fields with the volatile modifier will NOT survive serialization and deserialization. D. The values in fields with the transient modifier will NOT survive serialization and deserialization. E. It is legal to serialize an object of a type that has a supertype that does NOT implement java.io.serializable. Q: 06 Assuming that the serializebanana2() and the deserializebanana2() methods will correctly use Java serialization and given: 13. import java.io.*; 14. class Food {Food() { System.out.print("1"); 3

4 15. class Fruit extends Food implements Serializable { 16. Fruit() { System.out.print("2"); 17. public class Banana2 extends Fruit { int size = 42; 18. public static void main(string [] args) { 19. Banana2 b = new Banana2(); 20. b.serializebanana2(b); // assume correct serialization 21. b = b.deserializebanana2(b); // assume correct 22. System.out.println(" restored " + b.size + " "); 23. // more Banana2 methods 24. What is the result? A. Compilation fails. B. 1 restored 42 C. 12 restored 42 D. 121 restored 42 E restored 42 F. An exception is thrown at runtime. Q: 7 When comparing java.io.bufferedwriter to java.io.filewriter, which capability exists as a method in only one of the two? A. closing the stream B. flushing the stream C. writing to the stream D. marking a location in the stream E. writing a line separator to the stream 4

5 Question: 8 Given: 10. class MakeFile { 11. public static void main(string[] args) { 12. try { 13. File directory = new File( d ); 14. File file = new File(directory, f ); 15. if(!file.exists()) { 16. file.createnewfile(); catch (IOException e) { 19. e.printstacktrace The current directory does NOT contain a directory named d. Which three are true? (Choose three.) A. Line 16 is never executed. B. An exception is thrown at runtime. C. Line 13 creates a File object named d. D. Line 14 creates a File object named f. E. Line 13 creates a directory named d in the file system. F. Line 16 creates a directory named d and a file f within it in the file system. G. Line 14 creates a file named f inside of the directory named d in the file system. 5

6 Q: 09. Q:10. Which code, inserted at line 14, will allow this class to correctly serialize and deserialize? 6

7 A. s.defaultreadobject(); B. this = s.defaultreadobject(); C. y = s.readint(); x = s.readint(); D. x = s.readint(); y = s.readint(); Question: 11 Given: 10. public class Foo implements java.io.serializable { 11. private int x; 12. public int getx() { return x; 12.publicFoo(int x){this.x=x; 13. private void writeobject( ObjectOutputStream s) 7

8 14. throws IOException { 15. // insert code here Which code fragment, inserted at line 15, will allow Foo objects to be correctly serialized and deserialized? A. s.writeint(x); B. s.serialize(x); C. s.writeobject(x); D. s.defaultwriteobject(); Q

9 13. Given: import java.io.*; class Player { Player() { System.out.print("p"); class CardPlayer extends Player implements Serializable { CardPlayer() { System.out.print("c"); public static void main(string[] args) { CardPlayer c1 = new CardPlayer(); try { FileOutputStream fos = new FileOutputStream("play.txt"); ObjectOutputStream os = new ObjectOutputStream(fos); os.writeobject(c1); os.close(); FileInputStream fis = new FileInputStream("play.txt"); ObjectInputStream is = new ObjectInputStream(fis); CardPlayer c2 = (CardPlayer) is.readobject(); is.close(); catch (Exception x ) { What is the result? A. pc B. pcc C. pcp D. pcpc E. Compilation fails. F. An exception is thrown at runtime. 9

10 14. Given: bw is a reference to a valid BufferedWriter And the snippet: 15. BufferedWriter b1 = new BufferedWriter(new File("f")); 16. BufferedWriter b2 = new BufferedWriter(new FileWriter("f1")); 17. BufferedWriter b3 = new BufferedWriter(new PrintWriter("f2")); 18. BufferedWriter b4 = new BufferedWriter(new BufferedWriter(bw)); What is the result? A. Compilation succeeds. B. Compilation fails due only to an error on line 15. C. Compilation fails due only to an error on line 16. D. Compilation fails due only to an error on line 17. E. Compilation fails due only to an error on line 18. F. Compilation fails due to errors on multiple lines. 15. Given: import java.io.*; class Keyboard { public class Computer implements Serializable { private Keyboard k = new Keyboard(); public static void main(string[] args) { Computer c = new Computer(); c.storeit(c); void storeit(computer c) { try { ObjectOutputStream os = new ObjectOutputStream( new FileOutputStream("myFile")); 10

11 os.writeobject(c); os.close(); System.out.println("done"); catch (Exception x) {System.out.println("exc"); What is the result? (Choose all that apply.) A. exc B. done C. Compilation fails. D. Exactly one object is serialized. E. Exactly two objects are serialized. 16. Given: import java.io.*; class Directories { static String [] dirs = {"dir1", "dir2"; public static void main(string [] args) { for (String d : dirs) { // insert code 1 here File file = new File(path, args[0]); // insert code 2 here and that the invocation java Directories file2.txt is issued from a directory that has two subdirectories, "dir1" and "dir1", and that "dir1" has a file "file1.txt" and "dir2" has a file "file2.txt", and the output is "false true", which 11

12 set(s) of code fragments must be inserted? (Choose all that apply.) A. String path = d; System.out.print(file.exists() + " "); B. String path = d; System.out.print(file.isFile() + " "); C. String path = File.separator + d; System.out.print(file.exists() + " "); D. String path = File.separator + d; System.out.print(file.isFile() + " "); 17. Given: import java.io.*; public class TestSer { public static void main(string[] args) { SpecialSerial s = new SpecialSerial(); try { ObjectOutputStream os = new ObjectOutputStream( new FileOutputStream("myFile")); os.writeobject(s); os.close(); System.out.print(++s.z + " "); ObjectInputStream is = new ObjectInputStream( new FileInputStream("myFile")); SpecialSerial s2 = (SpecialSerial)is.readObject(); is.close(); System.out.println(s2.y + " " + s2.z); catch (Exception x) {System.out.println("exc"); 12

13 class SpecialSerial implements Serializable { transient int y = 7; static int z = 9; Which are true? (Choose all that apply.) A. Compilation fails. B. The output is C. The output is D. The output is E. The output is F. In order to alter the standard deserialization process you would override the readobject() method in SpecialSerial. G. In order to alter the standard deserialization process you would override the defaultreadobject() method in SpecialSerial. SECTION-2 Q: 01 Given: 11. public class Test { 12. public static void main(string [] args) { 13. int x = 5; 14. boolean b1 = true; 15. boolean b2 = false; if ((x == 4) &&!b2 ) 18. System.out.print("1 "); 19. System.out.print("2 "); 20. if ((b2 = true) && b1 ) 21. System.out.print("3 ");

14 What is the result? A. 2 B. 3 C. 1 2 D. 2 3 E F. Compilation fails. G. An exception is thrown at runtime. Q: 02 Given the command line java Pass2 and: 15. public class Pass2 { 16. public void main(string [] args) { 17. int x = 6; 18. Pass2 p = new Pass2(); 19. p.dostuff(x); 20. System.out.print(" main x = " + x); void dostuff(int x) { 24. System.out.print(" dostuff x = " + x++); What is the result? A. Compilation fails. B. An exception is thrown at runtime. C. dostuff x = 6 main x =

15 D. dostuff x = 6 main x = 7 E. dostuff x = 7 main x = 6 F. dostuff x = 7 main x = 7 Q: 03 Given: 13. public class Pass { 14. public static void main(string [] args) { 15. int x = 5; 16. Pass p = new Pass(); 17. p.dostuff(x); 18. System.out.print(" main x = " + x); void dostuff(int x) { 22. System.out.print(" dostuff x = " + x++); What is the result? A. Compilation fails. B. An exception is thrown at runtime. C. dostuff x = 6 main x = 6 D. dostuff x = 5 main x = 5 E. dostuff x = 5 main x = 6 F. dostuff x = 6 main x = 5 Question: 04 Given: 42. public class ClassA { 43. public int getvalue() { 44.int value=0; 15

16 45. boolean setting = true; 46. String title= Hello ; 47. if (value (setting && title == Hello )) { return 1; 48. if (value == 1 & title.equals( Hello )) { return 2; And: 70. ClassA a = new ClassA(); 71. a.getvalue(); What is the result? A. 1 B. 2 C. Compilation fails. D. The code runs with no output. E. An exception is thrown at runtime. 5. Given: class Hexy { public static void main(string[] args) { Integer i = 42; String s = (i<40)?"life":(i>50)?"universe":"everything"; System.out.println(s); What is the result? A. null B. life C. universe D. everything E. Compilation fails. F. An exception is thrown at runtime. 16

17 6. Given: 1. class Example { 2. public static void main(string[] args) { 3. Short s = 15; 4. Boolean b; 5. // insert code here Which, inserted independently at line 5, will compile? (Choose all that apply.) A. b = (Number instanceof s); B. b = (s instanceof Short); C. b = s.instanceof(short); D. b = (s instanceof Number); E. b = s.instanceof(object); F. b = (s instanceof String); 1.What is the expected output? public static void main(string[] args) { boolean stmt1 = "champ" == "champ"; SECTION-3 boolean stmt2 = new String("champ").equals(new String("champ")); boolean stmt3 = "champ".tostring()=="champ"; System.out.println(stmt1 && stmt2 && stmt3); Please choose only one answer: A>True B>False 2. Select the common methods, which are defined for both type String and type StringBuffer? Please choose all the answers that apply: 17

18 A> tostring() B> length() C> append(string) D> trim() E> equals(object) 3.Which of the statements would evaluate to true? public class Tester { public static void main(string[] args) { StringBuffer sb = new StringBuffer("javachamp"); String s = new String("javachamp"); boolean stmt1 = s.equals(sb) ; boolean stmt2 = sb.equals(s) ; boolean stmt3 = sb.tostring() == s ; boolean stmt4 = sb.tostring().equals(s) ; boolean stmt5 = s.equals(sb.tostring()) ; Please choose all the answers that apply: A> stmt1 B> stmt2 C> stmt3 D> stmt4 E> stmt5 4.Which of the statements will evaluate to true? Author: JavaChamp Team public class Tester { public static void main(string[] args) { StringBuffer sb1 = new StringBuffer("javachamp"); StringBuffer sb2 = new StringBuffer("javachamp"); boolean stmt1 =sb1.equals(sb2) ; boolean stmt2 = sb1 == sb2; String s1 = new String("javachamp"); String s2 = new String("javachamp"); boolean stmt3 = s1.equals(s2); boolean stmt4 = s1 == s2; Please choose only one answer: A> stmt1 B> stmt2 18

19 C> stmt3 D> stmt4 5.What is the expected output? public static void main(string args []) { String stmt = null; System.out.print(null+stmt); System.out.print(stmt+null); Please choose only one answer: A> RuntimeException is thrown because of the first print statement B> RuntimeException is thrown because of the second print statement C> nullnullnullnull D> nullnull E> compilation error 6. What is the result of compiling and running the following code? public static void main(string[] args) { StringBuffer buffer1 = new StringBuffer("javachamp"); StringBuffer buffer2 = new StringBuffer(buffer1); if (buffer1.equals(buffer2)) System.out.println("true"); else System.out.println("false"); Please choose only one answer: A> true B>false 7. What is the result of compiling and running the following code? public static void main(string[] args) { String s1 = null; String s2 = null; if (s1 == s2) System.out.print("A"); if (s1.equals(s2)) System.out.print("B"); Please choose only one answer: A> "AB" will be printed B> "A" will be printed followed be a NullPointerException thrown 19

20 C> "B" will be printed D> No output is produced E> Author: Yasser Ibrahim 8.Which of the following methods can be invoked by an object of Pattern class? Please choose all the answers that apply: A> compile B> matches C> group D> tostring 9. What is the result of compiling and running the following program? public class Tester { public static void main(string[] args) { String a = "javachamp"; String b = "javachamp"; String c = new String("javachamp"); System.out.print(a==b); System.out.print(a==c); System.out.print(b.equals(c)); System.out.print(b.equals(a)); Please choose only one answer: A> Compilation error B> falsefalsetruetrue C> truetruetruetrue D> truefalsetruetrue 20

21 10. What is the result of compiling and running the following code? public class Tester { public static void main(string[] args) { String stmt = "JavaChamp is here to help you"; for (String token : stmt.split("//s")) { System.out.print(token + " "); Please choose only one answer: A> JavaChamp is here to help you B> JavaChamp i here to help you C> No output is produced D> Compilation error 21